How fast can a electron orbit the nucleus?

Question

What is the most comon speed of an electron around a hydrogen nucleus? Is it typically near light speed?

Answer 1

The other responders are right in that it's not quite right to think of the electron orbiting the nucleus like a little planet. Nevertheless there are relativistic effects for the electron. The rough rule is that the electron's classical speed is about the charge it "sees" divided by 137. The electron might see more or less of the nuclear charge depending on whether it's closer or farther from the nucleus. For heavy elements like Uranium, the classical speed of the innermost electrons is a significant fraction of the speed of light.

Answer 2

The hydrogen atom is a quantum system, so speeds and sizes don't apply in the usual sense. The configuration of an electron around a proton is a smooth spherically-symmetric cloud. One might try to calculate the expectation value of the momentum of the electron (zero, I'm pretty sure), but that doesn't tell you very much. One might try to calculate the size as the expectation value of the position (zero) or of the radius (bohr radius), but that really tells you the size of the whole atom. It's just not a very sensible endeavor.

Answer 3

Electrons do not really orbit. However, an old type of quantum mechanics thoery (still taught as an introduction) is called the Bohr model of the atom. In this model electrons orbit. In this model the inner electrons are moving at a large fraction of the speed of light.

Answer 4

The laws of physics prevent us from knowing. The Heisenberg Uncertainty Principle limits the accuracy in any attempt to measure it.


The law states that the products of the known errors in position and momentum must be less than or equal to planks constant divided by 4 pi. In other words if we knew exactly where the electron was then its speed could be anything. Or if we knew its speed exactly then there would be no way to say what nucleus it orbited or where in the universe it was.

Answer 5

I believe the "speed" is close to speed of light, but keep in mind electrons do not orbit, per se.

They occupy probability clouds, and these clounds have shapes that may look like orbits (they're called orbitals) but it isn't as if the electron actually circles.

Answer 6

here the electro static force of attraction gives the necessary force so mv^2 /r = k ze^2 /r^2
v^2 = kze^2/mr
since it is an hydrogen atom z=1 so
v^2 = ke^2/mr =(9 X 10^9 X 2.56 X 10^-38)/9.11X10^-31 X .53X10^-10
from the above formula i think u can calculate
but by heisenberg priciple it is not possible to measure both the velocity and position at the same time accurately

Answer 7

The speed of an electron approaches the speed of light in a vacuum, but isn't as fast. Typically, it is 75% the speed of light.

c=3.0E8 m/s, therefore .75c = 2.25E8 m/s

Answer 8

1 electron year? term to ponder

Answer 9

dunno